Mold assembly for forming ophthalmic lens, method of producing the same, and method of producing ophthalmic lens using the mold assembly

Abstract

A mold assembly for forming an ophthalmic lens, the mold assembly comprising a first mold and a second mold which cooperate with each other to define therebetween a mold cavity having a profile following that of the ophthalmic lens, wherein the improvement comprises: at least one of the first and second molds being a coated mold consisting of a body portion including a backing surface having rigidity and mechanical strength enough to withstand a molding operation for forming the ophthalmic lens in the mold cavity, and a thermoplastic film retained on the body portion such that the thermoplastic film covers the backing surface of the body portion, the thermoplastic film having a molding surface which partially defines the mold cavity and which gives a corresponding one of opposite surfaces of the ophthalmic lens.

Description

1. Field of the InventionThe present invention generally relates to a mold assembly for forming an ophthalmic lens, a method of producing the mold assembly, and a method of producing the ophthalmic lens by using the mold assembly. More particularly, the present invention is concerned with such a mold assembly for forming the ophthalmic lens such as a contact lens or an intraocular lens, which mold assembly does not suffer from undesirable deformation during a molding operation for forming the intended ophthalmic lens, to thereby permit easy and economical production of an ophthalmic lens having a desired configuration, and an advantageous method of producing such a mold assembly. Further, the invention is concerned with a method of producing the ophthalmic lens with the desired configuration at a relatively low cost, by using the mold assembly.2. Discussion of the Related ArtThere are proposed various techniques for producing an ophthalmic lens by a mold assembly consisting of a fir...

AI Technical Summary

Benefits of technology

It is a second object of the invention to provide a method of producing such a mold assembly with relatively simple and inexpensive equipment.

It is a third object of the invention to provide a method of producing an accurately configured ophthalmic lens such as a contact lens or an intraocular lens at a relatively low cost, by using such a mold assembly.

In the mold assembly constructed as described above, at least one of the first and second molds of the mold assembly is a coated mold wherein the body portion is coated with the thermoplastic film which partially defines the mold cavity and has the molding surface for forming the corresponding one of the opposite surfaces of the ophthalmic lens to be obtained. Accordingly, the molding surface of the thermoplastic film is effectively supported or backed by the backing surface of the body portion, so that the molding surface given by the thermoplastic film is prevented from undesirable deformation during the molding operation for forming the ophthalmic lens. Therefore, the ophthalmic lens to be obtained by using the present mold assembly has the desired configuration. In addition, the coated mold is easily obtained by covering the backing surface of the body portion with the thermoplastic film. Further, the body portion of the coated mold can be repeatedly used by simply removing the used thermoplastic film therefrom and discarding it, after the molding operation.

According to the present method described above, the coated mold which is constituted by each of the above-indicated at least one of the first and second molds is easily obtained by a simple press forming operation in which the thermoplastic film is formed on or retained in close contact with the backing surface of the body portion. This method does not require the conventionally effected high-pressure molding using relatively rigid metallic dies.

According to the method described above, the coated mold constituted by each of the above-indicated at least one of the first and second molds consists of the body portion and the thermoplastic film retained on the body portion. In the present method, the thermoplastic film which gives the molding surface is backed by the backing surface of the body portion, so that the thermoplastic film is effectively prevented from being deformed during the molding operation for forming the ophthalmic lens. Accordingly, the obtained lens has an intended or desired optical surface configuration. In addition, the body portion of the coated mold can be repeatedly used, thereby effectively reducing the cost of manufacture of the mold assembly, and accordingly reducing the cost of manufacture of the ophthalmic lens.

Problems solved by technology

Moreover, the molds are easily deformed upon removal or releasing of the molded product therefrom, making it impossible to repeatedly use the molds in subsequent molding operations.

Such high-pressure molding, however, undesirably and inevitably requires expensive equipment.

If the thickness of the webs is relatively small, the male and female molds formed in the thin webs undesirably tend to be deformed during the molding operation for forming the contact lens.

Such high-pressure molding, however, undesirably and inevitably requires expensive equipment.

In this case, the soft contact lens molded in the deformed molds does not have the intended optical characteristics.

If the thickness of the thermoplastic film 10 is excessively small, the thermoplastic film 10 tends to be easily ruptured or torn, deteriorating the molding efficiency.

Further, the excessively thin thermoplastic film does not securely adhere to the body portion 8 due to the air entrapped between the thermoplastic film 10 and the convex surface 9 of the body portion 8.

On the other hand, if the thickness of the thermoplastic film 10 is too large, the molding efficiency is undesirably deteriorated, resulting in reduced productivity of the ophthalmic lens.

This would be difficult if the thermoplastic film 10 were not supported by the body portion 8.

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